[Significance of an increase of total IgE]

Under normal condition, serum IgE concentrations are low and controlled by complex regulating mechanisms. Increased IgE synthesis may be associated with a response of IgE antibodies to allergens or parasites. It may also betray a wider disorder in the regulation of IgE production, resulting in a rise of total IgEs of unknown specificity. Broadly speaking, high IgE levels are observed in two main circumstances: allergic ans parasitic diseases. In allergic diseases the diagnostic value of high IhE concentrations is modest, since a search for specific IgEs by cutaneous tests ot laboratory techniques (RAST) is more rewarding than total IgE determination. However, total IgE assays are useful in the detection of atopy in neonates at risk and the identification and therapeutic follow-up of allergic pulmonary aspergillosis. High IgE levels are frequently associated with parasitic diseases, especially helminthiasis. They also reflect a disorder of IgE homeostasis in some types of immunodeficiency, including the classical IgE hyperproduction syndrome. Except for this syndrome, high IgE concentrations merely constitute a secondary diagnostic factor in a wide pathology, but they often bear witness to a subjacent dysregulation of T-cell function.